Pressure sensing and control for semiconductor wafer probing

ABSTRACT

A wafer probing system includes a probe card assembly having a plurality of individual probe structures configured make contact with a semiconductor wafer mounted on a motor driven wafer chuck, with each probe structure configured with a pressure sensing unit integrated therewith; and a controller configured to drive the probe card assembly with one or more piezoelectric driver units response to feedback from the pressure sensing units of the individual probe structures.

DOMESTIC PRIORITY

This application is a division of U.S. patent application Ser. No.13/285,048, filed Oct. 31, 2011, now U.S. Pat. No. 8,963,567 thedisclosure of which is incorporated by reference herein in its entirety.

BACKGROUND

The present invention relates generally to semiconductor devicemanufacturing and, more particularly, to an apparatus and method forimproved pressure sensing control during wafer probing of integratedcircuits.

Integrated circuits are often manufactured on a semiconductor substrate,such as a silicon wafer. Typically, a single wafer will have numerousintegrated circuit (IC) devices formed thereon a lattice pattern. EachIC device has of numerous layers of circuitry and a collection ofexternal bonding pads, which are small sites made from a conductivematerial such as aluminum. The bonding pads eventually serve as thedevice's connections to the pin leads.

Since the packaging of a device is a costly procedure, it is desirableto test a device beforehand to avoid packaging faulty devices. Thetesting process involves initially establishing electrical contactbetween a probe card and the wafer, and thereafter running a series oftests on the devices on the wafer's surface. The probe card has acollection of individual electrical contact pins or probes that stand infor the normal pins and wire leads of a packaged device. The wafer ispositioned relative to the probe card so that the contact pins on theprobe card make contact with a wafer's bonding pads and probe pads whilea special tester runs a series of electrical tests on the wafer'sdevices. A wafer prober is used to position the wafer with respect tothe probe card.

In order to provide appropriately reliable electrical contact with adevice under test (DUT), numerous and diverse types of probes have beendeveloped in the technology, wherein it is normally recognized that eachprobe type necessitates the employment of a specific probing force. Aninsufficient contact force between the probe and the wafer will resultin an unreliable electrical contact, while an excessive contact forcewill result in damage to the probes or contact pads on the DUT.Currently, most systems which are employed for wafer testing do notincorporate sufficiently reliable structure or testing steps which willreadily or accurately determine the probe force that is being applied toeach pad on the DUT during implementation of the testing procedure.

Each probe technology has a characteristic probe compliance or springrate, and thus the correct probe force occurs at a specific probedisplacement. Consequently, a current wafer testing practice is tooverdrive or displace the wafer the specified distance into the probesystem. Unfortunately, the resulting forces may result in significantdeflection of the probe support structure. This is especially a problemwith probe arrays that incorporate a large number of probes. In thiscase, the amount of overdrive must be increased to overcome deflectionof the support structure. The actual amount of the resultant force isnot readily determinable and may be open to conjecture. Thus, a typicaloverdrive is ordinarily determined experimentally for one particularproduct, and through extrapolation or assumptions employed for allsimilar systems and products.

SUMMARY

In an exemplary embodiment, a wafer probing system includes a probe cardassembly having a plurality of individual probe structures configuredmake contact with a semiconductor wafer mounted on a motor driven waferchuck, with each probe structure configured with a pressure sensing unitintegrated therewith; and a controller configured to drive the probecard assembly with one or more piezoelectric driver units response tofeedback from the pressure sensing units of the individual probestructures.

In another embodiment, a method of implementing a wafer probing systemincludes positioning a semiconductor wafer mounted on a motor drivenwafer chuck to a preset position to initiate contact between the waferand a probe card assembly having a plurality of individual probestructures, with each probe structure configured with a pressure sensingunit integrated therewith; and upon detection of contact between atleast one probe structure and a surface of the wafer via a pressuresensing unit of the at least one probe structure, engaging a pluralityof piezoelectric driver units in response to feedback from the pressuresensing unit so as to perform fine adjustment of the at least one probestructure and ensure contact between the at least one probe structureand a surface of the wafer.

In another embodiment, a probe card assembly for wafer probing system,includes a supporting stage having a plurality of individual probestructures attached thereto, each probe structure configured with apressure sensing unit integrated therewith so as to detect contactbetween the probe structure and a surface of a wafer; wherein the probestructure further comprises a flexible probe arm having a first segmentand a second segment pivotally joined to one another by a connectionmechanism, and a probe tip disposed at a distal end of the secondsegment, such that contact between the probe tip and the wafer surfaceallows the second segment to pivot about the connection mechanism anddeflect away from a longitudinal axis of the probe structure.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the exemplary drawings wherein like elements are numberedalike in the several Figures:

FIG. 1(a) is a top view of a probe structure suitable for use inaccordance with an exemplary embodiment of the disclosure;

FIG. 1(b) is a side view of the probe structure of FIG. 1(a);

FIG. 2 illustrates a probe structure having an integrated pressuresensing unit using an optical detection technique, in accordance with anexemplary embodiment of the disclosure;

FIG. 3 illustrates a probe structure having an integrated pressuresensing unit using an electrical detection technique, in accordance withan exemplary embodiment of the disclosure;

FIG. 4 illustrates a probe structure having an integrated pressuresensing unit using a mechanical detection technique, in accordance withan exemplary embodiment of the disclosure;

FIG. 5 is a schematic diagram illustrating a system for improvedpressure sensing control during wafer probing of integrated circuits inaccordance with an exemplary embodiment of the disclosure, in whichzonal piezoelectric driver units are used for fine adjustment of probes;

FIG. 6 is a top view of the probe card assembly of FIG. 5, illustratingthe individual zonal piezoelectric driver units;

FIG. 7 is a flow diagram illustrating an exemplary method ofimplementing pressure sensing control during wafer probing using thesystem of FIGS. 5 and 6;

FIG. 8 is schematic diagram illustrating a system for improved pressuresensing control during wafer probing of integrated circuits inaccordance with another exemplary embodiment of the disclosure, in whichindividual (local) piezoelectric driver units are used for fineadjustment of probes; and

FIG. 9 is a flow diagram illustrating an exemplary method ofimplementing pressure sensing control during wafer probing using thesystem of FIG. 8.

DETAILED DESCRIPTION

It has been recently observed that inline test probing causes mechanicaldamage to material layers (particularly copper and enclosed low-kdielectric layers) on semiconductor chips. Such damage results insignificant yield loss and reliability degradation. Historically,cantilever probe cards used in manufacturing have applied downwardforces in the neighborhood of about 4 grams (g) at a rated overdrivecompliance (typically 2 mils). This 4 g of force has also proved robustin maintaining stable contact resistance at acceptable levels. However,with the introduction of ultra low-k (ULK) dielectrics, excessivedownward pressure may cause pad damage, as well as underlying structuredamage.

A common solution to this problem is to use probe cards built with a lowdown force (LDF) specification. This may be accomplished by the probesupplier modifying the physical dimensions of the probe needle to obtaina lower balance contact force (BCF). A typical example would be to ordera card with 1 gram per mil BCF rating (versus a 2 grams per mil BCF, forexample). However, a disadvantage of reducing the BCF would be anincrease in contact resistance due to the fact that less force isavailable to break thru any oxide coating on the Al/Cu pads.

Traditionally, spring-loaded probes are adapted to protect copper padand ultra low-k (ULK) dielectric materials from probing induced damage,as well as to make sure each probe makes good contact to the respectiveprobing pad. In such a case, probe pressure from probe tip overdrive maybe reduced by a spring-loaded probe tip and probe cards built with a lowdown force (LDF) specification. However, a conventional probe system isunable to determine whether or not each probe is making contact with apad, and thus mechanical damage by probe contact and overdrive may stilloccur.

Accordingly, disclosed herein are embodiments of an apparatus, systemand method of improved pressure sensing control during wafer probing ofintegrated circuits. In one aspect, a novel probe structure incorporatesa pressure sensing unit with each individual probe or pin, which unitsin turn enable a feedback control system to ensure that each probe makescontact with a corresponding landing pad. As described in further detailbelow, the feedback control system is configured to implement a fineadjustment of probes, either locally (regionally) or individuallythrough the use of a piezoelectric driver unit.

Referring initially to FIGS. 1(a) and 1(b), there is shown top and sideviews, respectively, of a probe structure 100 suitable for use inaccordance with an exemplary embodiment of the disclosure. The probestructure 100 includes a flexible probe arm 102 having a first segment104 and a second segment 106 pivotally joined to one another by aconnection mechanism such as a torsion spring 108 for example. Disposedat a distal end of the second segment 106 probe arm 102 is a probe tip110 configured to be brought in engagement with a semiconductor wafer(not shown in FIGS. 1(a) and 1(b)). As described in further detailbelow, a proximal end of the first segment 104 is secured to a probecard (not shown in FIGS. 1(a) and 1(b)), such that contact between theprobe tip 110 and a wafer surface allows the second segment 106 to pivotabout the torsion spring 108 and deflect away from a longitudinal axis112 of the probe structure 100.

The degree to which the second segment 106 pivots or deflects about thetorsion spring 108, and therefore the amount of pressure applied by theprobe structure 100 to a semiconductor wafer may be determine by the useof an integrated pressure sensing unit provided with each individualprobe structure. In this regard, several possible embodiments arecontemplated, as illustrated in FIGS. 2-4. For example, FIG. 2illustrates a probe structure 100 having an integrated pressure sensingunit 200 that uses an optical detection technique, in accordance with anexemplary embodiment of the disclosure. As illustrated, the integratedpressure sensing unit 200 includes an optical detector array 202 inproximity with the probe structure 100. The optical detector array 202receives an optical signal (dashed arrows) incident thereupon, a resultof an incident optical beam (solid arrows) directed upon the surface ofthe probe structure 100. The optical beam may originate from, forexample, a suitable optical source such as a laser (not shown).

Where the probe structure 100 is not yet in contact with the surface ofa wafer 204, or where the contact is light enough such that the probestructure is not bent or deflected, the optical detector array 202 willdetect a first type of optical signature associated with an unbent probestructure. On the other hand, as the probe structure 100′ is broughtinto contact with the surface of the wafer 204 with sufficient force soas to deflect the probe structure 100′ about its pivot point, thecharacteristics of received optical signal (dashed arrows) changes. Thedegree to which this signal changes is reflective of the appliedpressure to the probe structure 100′ and wafer 204.

In an alternative embodiment, FIG. 3 illustrates a probe structure 100having an integrated pressure sensing unit 300 that uses an electricaldetection technique. Here, the integrated pressure sensing unit 300includes a cantilevered electrode arm 302 in proximity with the probestructure 100. Both the electrode arm 302 and the probe structure 100are in electrical contact with detector circuit 304, which may be forexample part of a probe card assembly or a separate component. Based onthe deflection of the probe structure 100, the detector circuit maymeasure or detect a change in one or electrical circuit parameters suchas a short circuit condition, an open circuit condition, a change incapacitance, etc.

In the specific example of FIG. 3, the electrode arm 302 is disposedsubstantially in parallel with the longitudinal axis of the probestructure 100. As the probe structure 100′ is brought in contact withthe wafer 204 and begins to deflect, the distance between the end of theelectrode arm 302 and the probe structure 100′ decreases, possibly tothe degree that the electrode arm 302 and the probe structure 100′ comeinto contact with one another. This deflection condition may be detectedby the circuit such as by determining a short circuit between theelectrode arm 302 and the probe structure 100′, or perhaps a change incapacitance therebetween. Alternatively, it is contemplated that theelectrode arm 302 could be disposed to be in contact with the probestructure 100 when not deflected, such that deflection of the probestructure results in separation between the electrode arm 302 and theprobe structure 100′, thereby creating an open circuit.

In still an alternative embodiment, FIG. 4 illustrates a probe structure100 having an integrated pressure sensing unit 400 that uses amechanical detection technique. In this example, deflection detectionmay be implemented through the use of a strain gauge 402 that sensestorsion. As will thus be appreciated, an integrated pressure sensingunit for a probe structure may be implemented in a variety of ways suchthat each probe in a probe card assembly has its own pressure sensingunit. In this manner, the information detected from each pressuresensing unit may be used for a fine adjustment of the probes.

Referring now to FIG. 5, there is shown a schematic diagram illustratinga system 500 for improved pressure sensing control during wafer probingof integrated circuits in accordance with an exemplary embodiment of thedisclosure, in which zonal piezoelectric driver units are used for fineadjustment of probes. As is shown in FIG. 5, a semiconductor wafer 502is positioned on a wafer chuck 504, the height of which may be adjustedthrough the use of a driving motor 506 that is controlled by a systemcontroller 508. A probe card assembly 510 (supporting stage) has anumber of individual probe structures 100 associated therewith, such asthose embodiments described above, for example. The probe card assemblymay include any number of individual probe structures (e.g., 25, 50)configured for engagement with corresponding conductive pads 512 formedon the wafer 502. It should be appreciated at this point that the system500 is suitable for use with either a cantilever probe design or avertical probe design.

For purposes of simplicity, the probe structures 100 are not depictedwith any of the specific integrated pressure sensing unit embodimentsdescribed above, but is should be understood that at least one type ofsuch units are provided therewith. Collectively, the signals derivedfrom the individual pressure sensing units are depicted by the dashedregion in FIG. 5, with the signals being received by a sensor signalcollector 514 in communication with the controller 508. With the probecontact information obtained from the pressure sensing unitscommunicated to the controller 508 by the sensor signal collector 514,the controller 508 may initiate fine adjustment of probe pressure on thewafer 502 through one or more individually controllable zonalpiezoelectric driver units disposed in contact with the probe cardassembly 510.

In an exemplary embodiment, the piezoelectric driver units 516 mayinclude one or more piezoelectric actuators that are capable of dynamicand precise motion, even at nanometer scale dimensions. As shown moreparticularly in the top view of FIG. 6, a single piezoelectric driverunit 516 may control movement of a zone or region of the probe cardassembly 510. Here, four (4) exemplary zones are depicted, meaning thatindividualized actuation of a given one of the piezoelectric driverunits 516 will cause downward movement (i.e., precision heightadjustment) of the probe(s) most closely disposed in that zone. Itshould be appreciated that a greater or lesser number and locations ofthe zones may be employed.

Referring now to FIG. 7, there is shown a flow diagram illustrating anexemplary method 700 of implementing pressure sensing control duringwafer probing using the system of FIGS. 5 and 6. As illustrated in block702, the wafer is initially brought to a preset position and readied forprobe contact thereto. The pressure sensing units associated with eachprobe structure of the probe card assembly are activated, as shown inblock 704. Then, in block 706, the probe height is precisely adjusted byactivation of each of the zonal piezoelectric driver units. This resultsin the probe card assembly being actuated in the direction of the wafer.

As the probe card assembly and associated probe structures approach thesurface of the wafer, signals from each of the integrated pressuresensing units are monitored to determine whether any of the probes havemade physical contact with the wafer surface, as indicated in block 708.In accordance with decision block 710, so long as none of the probeshave made contact with the wafer, the method loops back to block 706 forcontinued adjustment of probe height via each of the piezoelectricdriver units. As soon as at least one probe is determined to havecontacted the wafer surface in decision block 710, then thepiezoelectric driver units are stopped as indicated in block 712.

At this point, the method transitions into a fine adjustment mode atblock 714. By way of example, if it detected that a single probestructure associated with piezoelectric driver unit number 4 (FIG. 6),then fine adjustment may involve actuating only the piezoelectric driverunit number 1, which is opposite in location to piezoelectric driverunit number 4. This precise, staged mode of fine adjustment is designedto allow further downward movement of a part of the probe card assembly,but without uniformly increasing the pressure on a probe or probes thatmay already be in contact with the wafer. In this manner, all probes mayeventually be brought into contact with the wafer.

Thus, as reflected in decision block 716, so long as all probes have notyet made contact with the wafer, the method 700 will loop back to block714 for continued fine adjustment of the individual zonal piezoelectricdriver units, focusing on zonal units whose probes have not yet madecontact with the wafer. Then, once all probes have been determined to bein contact with the wafer, the method proceeds to block 718 to beginchecking for proper electrical continuity between each probe and anassociated pad on the wafer. Although a probe may be in physical contactwith the wafer, it is still left to determine whether such contact isproperly located or whether the contact is at a sufficient pressure soas to provide desired electrical continuity. Accordingly, if all probeshave not passed a continuity check, then the method 700 proceeds toblock for further fine adjustment of individual zonal piezoelectricdriver units corresponding to the probes with insufficient continuity.The continuity check is repeated until it is determined at decisionblock 720 that all probes have passed. Once all probes have passed thecontinuity check, the method 700 may proceed to block 724 to beginelectrical testing of the wafer as known in the art.

As an alternative to zonal piezoelectric driver units, the granularityof the fine adjustment can be further increased by providing a dedicatedpiezoelectric driver unit for each probe structure of the probe cardassembly. Such an embodiment is depicted in FIG. 8, which illustrates asystem 800 for improved pressure sensing control during wafer probing ofintegrated circuits in accordance with another exemplary embodiment ofthe disclosure. As compared with the system 500 of FIG. 5, in the system800 of FIG. 8, the zonal piezoelectric driver units are replaced withindividual (i.e., local) piezoelectric driver units 816 for each probestructure. In this manner, each probe structure may be drivenindividually for precise adjustment.

With respect to precise adjustment, FIG. 9 is a flow diagramillustrating an exemplary method 900 of implementing pressure sensingcontrol during wafer probing using the system of FIG. 8. In block 902, acoarse adjustment is performed by driving the wafer stage motor so as tobring the wafer into a present position such that the probes structuresof the probe card assembly are in substantially close proximity to thesurface of the wafer. At block 904, a probe counter is set for the firstof the plurality of probe structures so that the first probe may besubjected to precision height adjustment. The first probe structure isadjusted in this regard by actuating the local, dedicated piezoelectricdriver unit for that probe structure. As described above, the firstprobe structure (as does each probe structure) has a local pressuresensing unit also associated therewith. Thus, as the first probe isbeing driven by its piezoelectric driver unit, the method 900 checks thesignal from the local pressure sensing unit.

If at decision block 910 it is determined that the first probe structurehas not yet made contact with the wafer surface, the piezoelectricdriver unit will continue its fine adjustment of the probe height untilwafer contact is made. At this point, the method 900 proceeds to block912, where the first piezoelectric driver unit is stopped, in terms ofits task of providing precision height adjustment. From this point, thefirst piezoelectric driver unit may now be used to apply a preset levelof fine overdrive adjustment to ensure proper electrical contact of thefirst probe structure to the wafer, as indicated in block 914. Decisionblock 916 determines whether the fine adjustment has been applied to thelast probe, and if not, the probe counter is incremented at block 918and the process loops back to block 906 for precision probe heightadjustment of the next probe structure. Finally, once the abovedescribed operations have been completed for the last probe structure,the method 900 may proceed to block 920 for final a continuity check ofthe probe structures before proceeding to electrical testing of thewafer.

As will thus be appreciated, among advantages of the disclosed device,system and method embodiments include an ability to prevent probeoverdriving, which can induce scratches or debris on the wafer surface.Overdriving can also damage dielectric layers, which in turn can lead todirect shorting between adjacent metal pads, and/or moisture ingressthrough poorly capped/sealed dielectrics that causes via opens inneighboring structures due to incomplete via etching.

In view of the above, the present embodiments may therefore take theform of computer or controller implemented processes and apparatuses forpracticing those processes. The disclosure can also be embodied in theform of computer program code containing instructions embodied intangible media, such as floppy diskettes, CD-ROMs, hard drives, or anyother computer-readable storage medium, wherein, when the computerprogram code is loaded into and executed by a computer or controller,the computer becomes an apparatus for practicing the invention. Thedisclosure may also be embodied in the form of computer program code orsignal, for example, whether stored in a storage medium, loaded intoand/or executed by a computer or controller, or transmitted over sometransmission medium, such as over electrical wiring or cabling, throughfiber optics, or via electromagnetic radiation, wherein, when thecomputer program code is loaded into and executed by a computer, thecomputer becomes an apparatus for practicing the invention. Whenimplemented on a general-purpose microprocessor, the computer programcode segments configure the microprocessor to create specific logiccircuits. A technical effect of the executable instructions is toimplement the exemplary methods described above and illustrated in FIGS.7 and 9.

While the invention has been described with reference to a preferredembodiment or embodiments, it will be understood by those skilled in theart that various changes may be made and equivalents may be substitutedfor elements thereof without departing from the scope of the invention.In addition, many modifications may be made to adapt a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope thereof. Therefore, it is intendedthat the invention not be limited to the particular embodiment disclosedas the best mode contemplated for carrying out this invention, but thatthe invention will include all embodiments falling within the scope ofthe appended claims.

The invention claimed is:
 1. A method of implementing a wafer probingsystem, the method comprising: positioning a semiconductor wafer mountedon a motor driven wafer chuck to a preset position to initiate contactbetween the wafer and a probe card assembly having a plurality ofindividual probe structures, with each probe structure configured with apressure sensing unit integrated therewith, the probe card assemblyincluding a plurality of zones spaced apart from one another, each zoneincluding at least one respective probe structure configured to beindividually actuated with respect to other probe structures included inother zones included in the plurality of zones so as to control movementof at least one zone with respect to at least one other zone among theplurality of zones; and upon detection of contact between at least oneprobe structure and a surface of the wafer via a pressure sensing unitof the at least one probe structure, engaging a plurality ofpiezoelectric driver units, driving at least one probe structure of afirst zone of the probe card assembly independently with respect to atleast one probe structure of a second zone of the probe card assembly inresponse to feedback from the pressure sensing unit, and driving the atleast one probe structure of a respective zone based on contact betweena surface of wafer and the at least one probe structure of a respectivezone so as to perform fine adjustment of the at least one probestructure and ensure contact between the at least one probe structureand a surface of the wafer.
 2. The method of claim 1, furthercomprising: following positioning the semiconductor wafer to the presetposition, driving the probe card assembly with each of the plurality ofpiezoelectric driver units until at least one of the probe structures isdetermined to have made contact with the surface of the wafer, whereinthe plurality of piezoelectric driver units comprise zonal piezoelectricdriver units, with each zonal piezoelectric driver unit configured tocontrol movement of a zone of the probe card assembly such thatindividualized actuation of a given one of the piezoelectric driverunits will cause precision height adjustment of probe structuresassociated with the zone; and performing a fine adjustment by drivingspecific zonal piezoelectric driver units associated with probestructures that have not contacted the wafer, and continuing the fineadjustment until all probe structures are determined to have contactedthe wafer.
 3. The method of claim 2, further comprising performingadditional fine adjustment of the probe card assembly with the zonalpiezoelectric driver units until each probe structure is determined tobe in electrical contact with the wafer surface.
 4. The method of claim1, further comprising: following positioning the semiconductor wafer tothe preset position, performing precision height adjustment for a firstof the plurality of probe structures by driving it with a first of thepiezoelectric driver units until the first probe structure is determinedto have made contact with the wafer surface, wherein each of theplurality of probe structures has a dedicated piezoelectric driver unitassociated therewith; and performing a fine adjustment of the firstprobe structure by further driving it with the first piezoelectricdriver units until the first probe structure is determined to be inelectrical contact with the wafer surface.
 5. The method of claim 4,further comprising: repeating, for each the remaining plurality of probestructures, driving with a corresponding one of the piezoelectric driverunits until each probe structure is determined to have made contact withthe wafer surface; and repeating, for each the remaining plurality ofprobe structures, performing the fine adjustment until each probestructure is determined to be in electrical contact with the wafersurface.
 6. The method of claim 1, wherein the pressure sensing unituses an optical detection technique to detect contact between the probestructure and the wafer surface, the optical detection techniqueincluding an optical detector array in proximity with the at least oneprobe structure, the optical detector array configured to receive anoptical signal incident thereupon in response to an incident opticalbeam directed upon the surface of the probe structure.
 7. The method ofclaim 1, wherein the pressure sensing unit uses an electrical detectiontechnique to detect contact between the probe structure and the wafersurface, the electrical detection technique including a detector circuitand a moveable arm in proximity with the probe structure, the detectorcircuit configured to detect a change in at least one electrical circuitparameter based on the deflection of the probe structure.
 8. The methodof claim 1, wherein the pressure sensing unit uses a mechanicaldetection technique to detect contact between the probe structure andthe wafer surface, the mechanical detection technique including a straingauge and a moveable arm in proximity with the probe structure to detecta strain torsion associated with contact between the probe structure andthe wafer surface.
 9. The method of claim 1, wherein the at least onepiezoelectric driver unit is a zonal piezoelectric driver unit.
 10. Themethod of claim 9, further comprising control movement of a zone of theprobe card assembly using the at least one a zonal piezoelectric driverunit such that individualized actuation of a given one of the at leastone zone piezoelectric driver unit precisely adjusts a height of theprobe structures associated with the zone.
 11. The method of claim 10,further comprising individually actuating a given zonal piezoelectricdriver unit will cause precision height adjustment of the at least oneprobe structure associated therewith.
 12. A method of probing a wafer,the method comprising: contacting a semiconductor wafer mounted on amotor driven wafer chuck using a plurality of individual probestructures, each probe structure configured with a pressure sensing unitintegrated therewith, the probe card assembly including a plurality ofzones, each zone including at least one respective probe structure;determining feedback from the pressure sensing units of the individualprobe structures; and driving at least one probe structure of a firstzone of the probe card assembly with at least one piezoelectric driverunit independently with respect to at least one probe structure of asecond zone of the probe card assembly in response to the feedback, anddriving the at least one probe structure of a respective zone based oncontact between a surface of wafer and the at least one probe structureof a respective zone.
 13. The method of claim 12, further comprisingpivoting a second segment of the at least one probe structure to deflectaway from a longitudinal axis of the at least one probe structure inresponse to contacting a probe tip of the second segment against asurface of the wafer.
 14. The method of claim 13, further comprisingdetecting contact between the at least one probe structure and the wafersurface based on an optical detection technique.
 15. The method of claim14, further comprising detecting the contact between the at least oneprobe structure and the wafer in response to detecting an optical signalthat is reflected from a surface of the at least one probe structure.16. The method of claim 13, further comprising detecting contact betweenthe at least one probe structure and the wafer surface based on anelectrical detection technique to detect contact between the at leastone respective probe structure and the wafer surface.
 17. The method ofclaim 16, further comprising detecting at least one electrical conditionin response to deflecting the at least one probe structure, anddetecting the contact between the at least one probe structure and thewafer based on the at least one electrical condition.
 18. The method ofclaim 17, wherein the electrical condition includes at least one of ashort circuit condition, an open circuit condition, a change incapacitance, and a change in resistance, based on deflection of the atleast one probe structure.
 19. The method of claim 13, furthercomprising detecting contact between the at least one probe structureand the wafer surface based on a mechanical detection technique.
 20. Themethod of claim 19, further comprising sensing torsion in response todeflecting the at least one probe structure, and detecting the contactbetween the at least one probe structure and the wafer surface based onthe torsion.